Bit.



J. D. MACDONALD, DECD. r. c. MACDONALD. ADMINISTRATOR.

BIT.

APPLICATION FILED APR. 29. 1913.

Patented Apr. 20, 1915.

IIIM M: A i

L N M a E WM VIM;

Til w 3 I v U 8 s JOSEPH D. MACDONALD, OF BUTTE,

MONTANA; FRANK C. MACDONALD ADMINISTRATOR OF SAID JOSEPH D. MAoDONALD, DECEASED.

BIT.

Application filed April 29. 1913.

To all whom it may concern:

Be it known that I, Josnrn D. MACDON- ALI). a citizen of the United States, residing at Butte, in the county of Silver-bow and State of Montana, have invented certain new and useful Improvements in Bits, of which the following is a specification.

My present invention pertains to an improvement in rock-drills, and has to deal more particularly with the construction of the bit and the means employed for securing the same in position upon the drill-body.

The invention is illustrated in the anneXed drawings, wherein:

Figure 1 is a perspective view of the drill with the bits inserted; Fig. '2 a vertical sectional elevation of the lower portion of the drill body with the bits removed; Fig. 3 a vertical sectional view, showing the bits in place, together with the locking device employed for holding the same; Fig. 4 a perspective view of one of the bits; Fig. 5 a bottom plan view of the drill-body with the bits and fastening device removed; Fig. (3 a similar view with the bits and locking device in position; Fig. 7 an elevation of the locking device; Fig. 8a vertical sectional view of the lower portion of the drill and a modified form of bit; Fig. 9 a perspective view of such modified bit; Fig. 10 a sectional elevation of the lower portion of a drill having a further modified form of bit mounted therein; and Fig. 11 a perspective view of one of the bits embodying such modified form.

The main object of the present invention is to provide a simple and effective drill, in which the bits may be readily positioned and secured, and this without the aid of any screws, bolts or the like, nor the necessity of employing any particular tool for re leasing the locking device.

In the preferred form of the structure the bits are reversible, that is to say, they are provided with two cutting edges, so that the second edge may be brought into operative position after the first edge has become worn or. perchance. injured.

A further object of the invention is to provide a bit having a cutting edge formed upon a curved line or the arc of a circle, so that the cutting edge will act upon an eX- tended surface.

Referring to the construction illustrated in Figs. 1 to 7 inclusive, 1 denotes the main Specification of Letters Patent.

Patented Apr. 20, 1915 Serial No. 764,423.

body of the drill. adapted to be secured to the usual drill-bar or other actuating mechanism. Said body has secured to it a headpiece '2, which for the purpose of manufacture is made separately and secured to the body 1, though in so far as the principles of my invention are concerned it is immaterial whether or not the head be formed integrally with the body. In the construction illustrated a threaded connection, as 3. is shown between the two members, and when assembled the parts will be sweated together, forming in effect an integral structure.

The outer end of the head is provided with a centrally-disposed opening which alines with a similar opening formed in the body, producing an elongated chamber 4-, in which is mounted the locking device for the bit. illustrated comprises a plug 5. of a diameter making a close fit with the chamber 4, the lower end of the plug carrying a pin or reduced member (3, adapted to coact with the bits hereinafter referred to and lock the same in place. A threaded stem 7, having a head 8, is passed downwardly through a washer 9, the stem being screwed into the upper end of the plug 5, and serving to hold a spring the washer and the upper face of the plug. The washer 9 is seated against a shoulder 11 formed at the junction of the chamber 4 and the longitudinal bore or opening 12 formed in the bit-body 1. 7 opening may be connected with the discharge of the drill-actuating mechanism. and a port 13 will preferably be formed in the body 1 opening into the bore 12 and atfording a discharge for the exhaust fluid employed in connection with the drill-actuating mechanism.

The outer end of the head or drill-body 1, as the case may be. is provided with two curved or arcuate slots M, 15. the slots curv ing toward each other, and cutting into the central opening or chamber 4. The adjacent faces of the two slots are vertical. and are parallel to the axis of the drill. as at 11'. 16. The upper or inner the slots is formedby a relatively short, outwardly inclined wall 17, which joins a reversely inclined wall 18, that extends outwardly toward the lower end of the drill, and in turn joins a third inclined face or Said device in the construction 1 10 between the lower face of a portion of each of Z Said bore or wall 19, said wall extending inwardly toward the base or outer end of the drill. In other words, each slot may be said to comprise a curved vertical wall, opposite which are two inclined walls which are likewise curved upon the same radius as the curved wall, while above the outer edge of the vertical Wall there is provided a fourth wall which is inclined outwardly from said vertical wall, forming a triangular recess with the adjacent outer inclined wall. These curved slots open through the side walls oi the body or head and the bits (which are of a form to make a close fit with the walls thereof) are moved endwise therein and by reason of the formation of the walls they are held against outward movement. In other words, the inward inclination of the wall 19 holds the bit in place. A bit adapted to fit into the slot thus produced is shown in perspective in Fig. 4. It is formed of a single piece of metal, curved in outline to fit in the slot in which it is adapted to be seated, andis provided with two oppositely-disposed edges 20, 21. It has a vertically-disposed side Wall 22, adapted to contact with the wall 16 or 16?, as the case may be, and two relatively long inclined faces 23, 24, adapted to contact with the inclined walls of the slot and form a locking engagement therewith to prevent outwardmovement in line with the axis of the drill.

To prevent the endwise shifting of the bits in the slots in which they are seated, each bit is provided with a vertically-disposed groove 25, formed therein adjacent the wall 22, said groove or channel receiving the locking pin 6 when the bits are brought to that position where the slots therein coincide with the pin.

When it is desired to position the bits, the operator will push the pin 6 and the plug 5 inwardly, compressing the spring 10, and then slip the bits into the seats and bring the grooves or slots 25 thereof into alinement with the pin. \V hen this takes place, the spring 10 will project the pin into the slots, as shown in Fig. 3, thereby holding the bits against further movement, until the pin is again forced into or retracted from locking engagement with. the bits.

It will thus be seen that the bits are well supported throughout, being positively held against movement, and this by a very simple arrangement.

It will be readily appreciated that the bits are reversible, and inasmuch as each bit and the slots 14 and 15 are formed upon the same radius, they are interchangeable.

In so far as the generic invention is concerned, it' is not essential that the bits be reversible, and in Figs. 8 and 9 there is shown a construction wherein the bits are provided with one cutting edge only, as indicated by 26. The slots, of course, are

position, however,

modified at their inner portions, or inother words, are squared so as to receive the flat face 27 of the bit. The bits arelocked in in the same manner as those above referred to, and the slots and bits are formed upon the same radius, so that the bits are interchangeable and may be as readily positioned as the form first described.

A still further modification is illustrated in Figs. 1.0 and 11, the bit in this instance being arcuate in form and rovided' with oppositely-disposed cutting e ges 28 and 29. The bit is provided upon its outer curved face with a V shaped recess 30, adapted to interlock with a complemental projection 31, extending into the slot formed in the head to receive the bit. A vertically-disposed recess 32, substantially semicylindrical in form, is designed to receive the locking pin or member 6 as in the other forms.

Having thus described my invention, what claim is:

1. I11- combination with a drill-body having two oppositely-disposed arcuate slots in its outer end, said slots being undercut and extending from edge to edge of the body and into a centrally-disposed chamber formed axially of the body; an arcuate bit removably mounted in each of said slots, said bits having at least one cutting edge following the curve of' the bit; and means mounted in the central chamber for holding the bits in place.

2. In combination with a drill-body having two oppositely-disposed arcuate slots in its outer end, said slots being undercut and extending from edge to edge of the body and into a centrally-disposed chamber formed axially of the body; an arcuate bit, removably mounted in each of said slots, said bits being of a cross-section to fit the slots, with their cutting edges following the curve of the bit and extending outwardly beyond the end of the body; and means mounted in the central chamber for holding the bits against movement.

3. In combination with a drill-body having an arcuate slot extending across its outer end, the walls thereof converging toward the outer open portion of the slot; an arcuate bit having a cross-section of substantially the same contour as the slot, and seated therein; and means for locking the bit in place.

4. In combination with a drill-body having a pair of arcuate slots formed in the outer end thereof, said slots having an irregular cross-section; an arcuate bit, having a similar cross-section, mounted in each slot, each bit having a recess formed in its side face; and a locking member carried by the drill adapted to enter said recesses when the bits are positioned, and hold the same against endwise movement.

meat-1a 5. In combination with a drill-body having a pair of arcuate slots formed in the outer end thereof, said slots being irregular in cross-section, and passing between their ends into a chamber formed in the drillbody; a bit mounted in each slot, said bits\ in cross-section being similar to the slots and curved to fit the same, each bit having a recess formed in its side face; and a spring-pressed lunger mounted in said chamber and a apted to enter the recesses formed in the bits.

6. A bit arcuate in outline, polygonal in cross-section, and having a cutting ed e following the curvature of the body, an likewise provided with a locking recess in one of its side faces.

7. A bit arcuate in outline and provided with oppositely-disposed parallel cutting edges following the curvature of the body, one side of the bit having a locking recess formed therein.

8. A bit arcuate in outline and provided with a cutting edge, one face of the bit having a locking slot or recess formed therein at right angles to the cutting edge.

9. In combination with a drill-body having a continuous arcuate slot in its outer end extending from edge to edge of the body, the walls of said slot being irregular in form; an arcuate bit having a section of sulstantially the same contour as the slot, seated in said slot and making an inter-locking contact therewith; and means for preventing endwise movement of the bit in the slot.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

JOSEPH D. MACDONALD.

Witnesss:

FRANK GRIFFIN, HARRY R. HIBBE'I'I. 

